scribnee



(No Model.) l v 2 sheets-sheen 1'.

- G. E. SGRIBNER.

MULTIPLE SWITGHBOARD SYSTEM.

Patented Oct. 18', 1892.

Za'rzesses.-

07/1 Lawa,

(No Moden.) '2 sheets-sheet 2.

` C. E. SGRIBNER. MULTIPLE SWITGHBOARD SYSTEM.

In/verdor.' (272,@ Esci/25238278 :gg tI/r'u ns I Z015 nesses:

THE Nonms Pafans o., wuumarou n c UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VESTERN ELECTRIC COMPANY, OF SAME PLACE.

M U LTI PLE-SWITCH BOARD SYSTEM.

SPECIFICATION forming part of Letters Patent N o. 484,612, dated October 18, 1892.

Application led January 2l,V 1892. Serial No. 418,823. (No model.)

To al? whom t may concern.' stood by reference to the accompanying drawle 1t known that I, CHARLES E. SCEIBNER, ings, in whichw a citizen of the United States, residing at Chi- Figure l is a diagram illustrative of three cago, in the county of Cook and State of Illitelephone-lines connected with switches on 55 5 nois, have invented a certain new and useful each of two switchboards, including differen- Improvement in Multiple Switchboard Systially-wound individual annunciators and tems, (CaseNo. 283,)011 which the followingis keyboard apparatus at each of the boards. afull,clear, concise, and exact descriptiomref- Fig. 2 is a more simple diagram of the cirerence being had to the accompanying drawcuits of two telephone-lines and of an opera- 6o ro ings, forming a part of this specication. tors outfit.

My invention relates to that class of tele- The telephone-line a of station l of Fig. l phone-exchange systems in which the teleextends to the springs of the switches a a2 phone-lines are permanently connected each of the line, and by the branch o3 through the with the springs and the test-pieces of the winding a4 of the individual annunciator to 65 I5 different switches thereof and the individual ground. The portion or branch ai of this line annunciator permanently connected in a ciris connected with the frames or test-pieces of cuit leading to ground from a portion of the the switches ci CL2 and to ground through reline between the springs of the switches on sistance a@ at the central office. The branch one side and the test-pieces of the switches connection cextends from this wire athrough 7o zo on the other side. the other dierential winding as of the indi- The object of my invention is to so arrange vidual annunciator to ground. the circuits of the individual annunciators At station 2 I have shown the circuits of with respect to the circuits of the operators the subscribers outfit. The telephone-line b outfits at the different boards that when any extends in two branches h b2 to the central 7 5 25 two lines are connected together current sent office. The branch b is permanently confrom either subscribers station, as for clearl nected with the springs of the switches b3 b4. ing-out purposes, will not throw down the in- The branch b5 from this limb extends through dividual annunciator of either of the lines. one ofthe windings of theindividual annun- My invention consists more particularly in ciator h6 to ground. The other limb or re- 8o 3o winding each individual annunciator differturn portion b2 of the metallic circuit of staentially and connecting the branch of the tion 2 is connected permanently with the line connectedwith the springsof theswitches frames or test-pieces of the switches h3 b4.

- through one of the differential windings and A branch hlfrom this limb h2 extends through the branch or portion which connects the the other winding of the individual annun- 85 3 5 test-pieces through the other of the dierenciator 196 to ground. The circuit of the teletial windings. The circuits are so arranged phoneline c of station 3 isconnected with that when the telephone at a station is hung the switches c c2 and with the individual anon the switch and the generator turned curnunciator c3 in the same manner as the cirrent will be sent from ground at the said stacuit a of station l is connected with its switch 9o 4o tion over the portion of the line connected a. a2 and its individual annunciator,he1eto with the springs of the switches and thence fore described. l through one winding of the individual an- In Fig. 2 the metallic circuit d of station 4 nunciator to ground, and the annunciator is is shown connected with its switches CZ d2 d3 thus operated. IVhen two lines are conand with the differential windings of indi- 9 5 45 nected, the circuits are such that if the genvidual annunciator (Z4 after the manner of erator is operated at either station, current circuit b of station 2, Fig. l, heretofore dewill pass through both coils of each of the scribed. annunciators and the magnets thereof will The telephone-line e of station 5, Fig. 2, is thus be rendered practically neutral and grounded after the manner of line a of staroo 50 neither annunciator will be thrown down. tion 1, Fig. 1.l This line eis permanently con- My invention will be more readily undernected with the springs of switches e e2 e3,

and is provided with a branch connection e4 through one of the windings of theindividual annunciator e5. The portion of this line connecting with the test-rings of the said switches is provided with a branch e6, extending through the other winding of said individual annunciator e5 to ground.

The plugs ff of the outfit shown in Fig. 2 are of usual construction. The clearing-out annunciator f2 is in a bridge between the sleeve-strand and tip-strand of the cords. The telephone f3 when in circuit is bridged between the same strands, the center of the coil of the telephone being provided with a grounding-branch f4 in a well-known way in order that the telephone may be used for testing. The branch f5 extends through the usual retardation-coil f6 and thence through a test-batteryf7. The test-battery may be common to as many sets of cords as may be convenient.

Vlien the telephone-as, for example, the telephone at station 4'-is hung on the switch and the generator operated, current will he sent through one winding only of the individual annunciator d4, and hence the shutter will be thrown down. Suppose, however, that the plug f were inserted in one of the switches of the line of station 4-for example, switch d. The tip of said plug would rest against the spring of said switch, and the sleeve of said plug would be in contact with the test ring or frame of said switch. In such case, suppose the telephone at station 4 hung on the switch so as to connect the switch-lever with the ground branch including the generator, and suppose the generator to be operated. Current would be sent over line d to the spring of switch d', and there the current would divide, one path leading through one winding of the individual annunciator d4 and the other path through the other winding thereof, and in such case the annunciator will not be operated. Suppose that not only the plug f were inserted in switch d', but also that the plug f' were inserted in the switch e of the line e of station 5. In the latter case current would be sent also in derived circuit through both of the windings e4 c6 of individual annunciator e5 of said line e.

I will now trace the circuits which would be then formed from the generator at station 4. First, the circuit would be from ground at station 4 to the point of division at the spring of switch d', from thence one branch would be the permanent branch through coil d5 of individual annunciator d4. The other path would be traced from the spring of switch d to the tip of plugf, and thence through the clearing-annunciatorf2, and thence back to the sleeve of switch f, and thence to the testpiece of d', and thence through the other winding d6 of the individual annunciator d4 to ground. Assuming now, as before stated, that plugf is inserted in switch e', the wire between the strands of the cords, which wire includes the clearing-out annunciator f 2, will be, accurately speaking, a bridge-wire. The current will therefore pass to the tip of plug f', and thence to spring of switch e', and thence through the coil e4 of the indlvidual annunciator c5 to ground; also, current will pass from thel other end of the bridge including the clearing-out annunciator f2 to the sleeve of plug f and thence, as before described, through the dierential winding e of individual annunciator e5.

As shown in Fig. 1, the lines of station 2 and 3 are connected upon the second board in the manner assumed with respect to the lines of stations 4 and 5 of Fig. 2. Suppose the operator at the first board, having received a call from the subscriber of station 1, has inserted plug g in switch a and received an order for connection with one of the lines b or c, we will say line b. The operator by applving the tip of plug g to the frame of switch c and listening at her telephone g2, connected in a bridge between the strands of the cords of plugs g g', will close circuit from test-bat tery g3 upon the line, and will know that the line called for is busy. It', however, a line not in use were tested, she would get no sound in her telephone, and would know that the line was free. This testcircuit is old and well known. Itis, however, specially adapted for use in connection with my invention herein, lwhich relates, as before stated, more particularly to the manner f arranging the circuits of the individual annunciators.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The combination, with a telephone-line extending from the subscribers station to the central oflice, of two or more switches, one portion of the line being permanently con nected with the springs of said switches and the other portion or branch thereof being connected with the test-pieces of said switches, and an individual annunciator included between said branches or portions of the telephone-lines, said individual annunciator being wound differentially and provided with a branch connection to ground, substantially as specified.

2. A telephone-line connected with an individual annunciator at the central olce in two branches or limbs, each branch or limb including a diderent dierential winding of said individual annunciator, whereby current sent over one limb will operate the annunciator, while current sent over both limbs will render said individual annunciator neutral and prevent the operation thereof, substantially as specified.

3. A telephone-line extending from the subscrib'ers station to the central office, one portion thereof being connected with the spring or springs of one or more switches and the other portion thereof connected with the testpiece or test-pieces of the same switches, and an individual annunciator wound differen- IOO IIO

IZO

tially, one dierential winding being included in one portion of the telephone-line and the other differential winding thereof being included in the other portion thereof, said differential coils being provided with a. ground connection, in combination with a, connecting device for insertion in one of the switches and a clearing-out annunciator connected in a bridge between the contacts of said connecting device, whereby current sent to line from subscribers station will be directed through both the dierential windings of lthe individual annunciator, substantially es specified.

4. The combination, with two telephonelines, each connected with switches on dii'erent switchboerds, and each including a different individual annunciator Wound differentially and provided with a, ground connec- In witness whereof I hereunto subscribe my 3o neme this 14th day of December, A. D. 1891.

CHARLES E. SCRIBNER. Witnesses:

GEORGE P. BARTON, M. JEANE TALLETT. 

